1. Technical Field
The invention relates generally to semiconductor device packaging, and more particularly, to methods of forming wire and solder bonds.
2. Background Art
Simultaneous use of wire bond and solder bond structures in the semiconductor industry is increasing. In one example, wire and solder bonds are advantageous for use in multi-part wafers (MPWs), which are currently increasing in popularity. Some of these MPWs include chips that require both wire bonds and solder bonds designed into a common reticle, i.e., they are fabricated together. In a solder bond, a solder joint flip chip connection to a substrate is made where the surface tension forces of the molten solder controls the height of the joint and supports the weight of the chip. The solder bond is oftentimes referred to as a controlled collapse chip connection (C4). In a wire bond, a wire is joined to an opening in the chip. Where both types of bonds are used, the fabrication process must be capable of opening both wire bond and solder bond final via structures in parallel.
The ability to create both wire bond and solder bond structures within a single processed part extends beyond use with MPWs. There are certain chip products (or test sites) that also require both solder and wire bond access points within the boundary of the individual chip itself. For example, in the case of parts being built for stacked packages, wherein the chips must make solder bond connections to other chips within the stack, but also a wire bond connection out to the package substrate or laminate. Simultaneous use of wire and solder bonds may also be advantageous for a technology qualification test-site. For example, it may be preferred to have both types of connections for a single common test site in order to enable qualification of front-end-of-line (FEOL) and back-end-of-line (BEOL) structures in both wire and solder bond packaging environments, but without having to design and build two different test-sites.
Generating wire and solder bonds together presents a number of challenges. For example, some of the processes used for each type of bond are detrimental to the other type of bond.